R Puppis

R Puppis (R Pup) is a variable star in the constellation Puppis. It is a rare yellow hypergiant and a member of the open cluster NGC 2439. It is also an MK spectral standard for the class G2 0-Ia.[7]

R Puppis
Location of R Puppis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Puppis
Right ascension  07h 40m 52.597s[1]
Declination −31° 39′ 40.20″[1]
Apparent magnitude (V) 6.50 - 6.71[2]
Characteristics
Spectral type G2 0-Ia[3]
U−B color index +0.85[4]
B−V color index +1.18[4]
Variable type SRd[2]
Astrometry
Radial velocity (Rv)+68.22[1] km/s
Proper motion (μ) RA: −2.265[1] mas/yr
Dec.: +3.349[1] mas/yr
Parallax (π)0.1732 ± 0.0288[1] mas
Distanceapprox. 19,000 ly
(approx. 5,800 pc)
Absolute magnitude (MV)−7.8[5]
Details
Radius477[1] R☉
Luminosity96,607[1] L☉
Surface gravity (log g)0.30[6] cgs
Temperature4,659[1] K
Metallicity [Fe/H]−0.25[6] dex
Other designations
CD−31°4910, GSC 07106-03582, HIP 37415, HR 2974, HD 62058
Database references
SIMBADdata
NGC 2439, with R Puppis the brightest star

Variability

R Puppis was identified as a variable star in 1879, and described as having a range of over a magnitude.[8] Numerous observations over the following 100 years failed to confirm the variations, until the 1970s when clear brightness changes were observed.[9] These were confirmed by later observations, but with a total visual amplitude of only about 0.2 magnitudes.[8]

Variable stars such as R Puppis have been described as pseudo-Cepheids, because they lie above the high-luminosity portion of the instability strip and their variations are similar to those of Cepheids although less regular.[8]. R Puppis is formally classified as a semiregular variable of type SRd, meaning F, G, or K giants or supergiants.[2]

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References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....1.2025S.
  3. Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
  4. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  5. Arellano Ferro, A.; Parrao, L. (1990). "Colour excesses and absolute magnitudes for non-Cepheid F-G supergiants from uvbybeta photometry". Astronomy and Astrophysics. 239: 205. Bibcode:1990A&A...239..205A.
  6. Usenko, I. A.; Kniazev, A. Yu.; Berdnikov, L. N.; Kravtsov, V. V. (2011). "Spectroscopic studies of Cepheids (S Cru, AP Pup, AX Cir, S TrA, T Cru, R Mus, S Mus, U Car) and semiregular bright supergiants (V382 Car, HD 75276, R Pup) in the southern hemisphere". Astronomy Letters. 37 (7): 499. Bibcode:2011AstL...37..499U. doi:10.1134/S1063773711070061. S2CID 122968535.
  7. Garcia, B. (1989). "A list of MK standard stars". Bulletin d'Information du Centre de Données Stellaires. 36: 27. Bibcode:1989BICDS..36...27G.
  8. Eggen, O. J. (March 1983). "Pseudocepheids. I. R Puppis, HR 4441, HR 4511, and AI CMi". Astronomical Journal. 88: 386–403. Bibcode:1983AJ.....88..386E. doi:10.1086/113323.
  9. Stift, M. J. (September 1978). "R Pup - a Variable after all". Information Bulletin on Variable Stars. 1473: 1. Bibcode:1978IBVS.1473....1S.
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